Lentiviral-mediated Transfer Of CDNF Promotes Nerve Regeneration And Functional Recovery After Sciatic Nerve Injury In Adult Rats

Objective:Peripheral nerve injury is a common clinical injury, which is usually caused by transportation accidents, natural disasters and other traumatic or the iatrogenic side effects of surgery.To study the effect of CDNF on peripheral nervous injury, we applied overexpression of CDNF in a rat sciatic nerve transection model to investigate the effect of CDNF on sciatic nerve regeneration.Methods:To create a better environment to enhance the therapeutic effects of nerve growth factors, we combined nerve conduits with gene therapy in this study.A rat sciatic nerve transection model was used in this study.(1) At weeks 2,4,6,8 after surgery, we estimated the functional nerve recovery of the rats using walking track evaluation.(2)At 4 weeks after injection, we tested the CDNF content in the distal sciatic nerve from each group and the normal nerve using Western blotting analysis.(3)We evaluated sciatic nerve regeneration after surgery using light and electron microscopy. After harvesting the newborn nerve at week 4 and week 8, we tested the longitudinal section of the newborn and normal nerve using HEstaining. We investigated the axonal regeneration by staining NF200-positive axons in the regeneration cables and normal nerves. Longitudinal sections of the sciatic nerve from the regeneration cables and normal nerves were stained for S-100, a Schwann cell marker, and the percentage of S-100 positive stained area was also statistically analyzed.(4)Ultra-thin sections were also observed under a transmission electron microscope at 8 weeks after injury.(5) As a simple and direct measure of CDNF effect on the reinnervation of target muscles, we weighed the gastrocnemius muscles at 4 weeks and 8 weeks after injury in all groups.Results:(1)We observed notable overexpression of CDNF protein in the distal sciatic nerve after recombinant CDNF lentiviral vector application.(2)HE staining revealed better ordered structured in the CDNF-treated group at 8 weeks post-surgery. Quantitative analysis of immunohistochemistry of NF200 and S-100 in the CDNF group revealed significant improvement of axonal and Schwann cell regeneration compared with the control groups at 4 weeks and 8 weeks after injury.(3)The thickness of the myelination around the axons in the CDNF group was significantly higher than in the control groups at 8 weeks post-surgery.(4)The CDNF group displayed higher muscle weights and significantly increased sciatic nerve index values.Conclusion:Our findings suggest that CDNF gene therapy could provide durable and stable CDNF protein concentration and has the potential to enhance peripheral nerve regeneration, morphological and functional recovery following nerve injury, which suggests a promising strategy for peripheral nerve repair.